Method of stereoscopic projection



Sept. 8, 1936. A. l.. BARNES METHOD OF STEREOSCOPIC PROJECTION FiledJan. 5, 1934 5 sheets-sheet 1 Sept. 8, 1936. A. I fBRNEs METHOD OFSTEREOSCOPIC PROJECTION 3 Sheets-Sheet '2 Filed Jan. 5, 1934 ZZf/z, L.Bar/z e@ Sept. 8, 1936. A. l.. BARNES METHOD OF STEREOSCOPIC PROJECTIONFiled Jan. 5, 1954 3 Sheets-Sheet 3 Patented Sept. 8, 1936 Ar OFFICE andmesne assignment trustee, ,Wilmette Ill.

s, to `ioseph lil. Hinshaw,

Application January 5, 193i, Serial No, 705,342

I Claim.

My invention relates to method of stereoscopic projection, andespecially third dimension mothe illumination for projection and at thesame time improve the projection by eliminating al1 flicker and darkintermissions caused by various shutters. I propose to do this byproviding a method of projection by which pictures may be projected onthe screen continuously, and I preferably accomplish` this by employingsynchronized projection light switches instead of the customaryshutters.

My method is perfectly suited for producing pictures in color fromrecords representing monochromes of the object photographed bysuperimposing a plurality of monochrome images on the projection screen;such superimposition by my method increases the illumination and isparticularly advantageous to the use of polarized light.

f course, if the superimposed images on the projection screen wereviewed with the naked eye the phenomenon customarily called parallax isexperienced and no stereoscopic eiect can be gained. However, as beforestated, I employ analyzing means in iront of the eyes so as to permitone eye to view only the rays of light which make up the image for thatparticular eye. Analogous analyzing means are employed for the other eyeand permit only the light rays of the image having a dierent viewpointto be viewed by that eye. I propose to use a pair of spectacles whichare adapted to perform this analyzing function and may useNicols prismof Iceland spar or herapathite crystals or other polarizing means. Theeye pieces in the spectacles to be Worn are the analyzers and are onlytwo transparent means of polarizing the light in diierent planes. Thecrystal eye piece for one eye is rotated 90 degrees on its axis fromthat for the other eye; that is, if the twoI eye pieces were so placedthat both of .them polarized light in parallel planes and then one ofthem were to be rotated through an angle of 90 degrees, it wouldpolarize light in planes at 90 degrees to the plane of polarized lightfor the other eye piece. By polarizing light in planes at 9 0 degreesthe light passing one cannot pass the otherdue to the peculiarity oflight rays when plane polarized. I take advantage of this peculiarityand therefore use these spectacles as analyzers of the projected light,and as a result each eye will analyze only the (Cl. S23-16.6)

light in the plane of polarization of its particular analyzer. Thus thelight of the images photographed from two points of view are projectedwith light vibrating in planes at right angles and received respectivelyin like manner by analyzers; one eye views the image as from oneviewpoint While the other eye views it as from a spaced viewpoint, andneither image interferes with the proper perception of the other image.True third dimension eiect is gained and the images may be projected intheir true colors and perceived in the same true colors.

Some attempts at stereoscopic projection have been made but theapparatus and methods heretofore devised have resulted in eye strain dueto the fact that one eye only is permitted to view the image at onetime. This eye strain is caused by the intermittent obliteration by ashutter of the view for one eye While the other eye is viewing the imageas from one point of view. This constant interruption of the lightreaching either eye is a strain on the rectifying nerves and producesheadache; this is one reason why previous methods and apparatus ofstereoscopic projection have been unsuccessful. My method eliminatesthis difficulty by making it possible for both eyes to view an image atall times, and since the conventional shutter of the ordinary projectionmachine is eliminated, the eyes are also considerably aided by theelimination of the objectionable flicker. Thus it is possible for anobserver to view a motion picture and perceive the third dimension eectin absolute comfort and ease. Ii the images are projected in colorinstead of in monochrome the eyes of the observer will be additionallyrested by the naturalness of vision in its true colors of light. Alsothe employment of a separate projection lamp for each color image willincrease the illumination of the composite image on the projectionscreen to such an extent that small detail mayl be perceived easily andwithout effort on the part of the observer.

Other objects will appear hereinafter.

My invention may be best understood by reference to the accompanyingdrawings, in which:

Fig. l is a plan diagrammatic view illustratingv my projection apparatusand analyzing means;

Fig. 2 is a sectional diagrammatic view taken substantially on the line2--2 of Fig. 1;

Fig. 3 is a sectional diagrammatic view taken substantially on the line5 of Fig. 1;

Fig. 4 is a diagrammatic plan of the electrical circuitand commutatormeans' preferably employed by me in my projector;

Fig. 5 is a sectional view taken substantially on the line 1 1 of Fig.4; y

Fig. 6 is a sectional view taken substantially on the line 8-8 of Fig.4;

Fig. 7 is a horizontal sectional plan of my projecting apparatus; and

Fig. 8 is a front elevational view with part of the housing in section,taken substantially on the line lil-I5 of Fig. 7.

Referring now to Figs. 1, 2, and 3, my method is shown diagrammaticallyand is especially adapted for use with nlm produced from exposure in mystereoscopic camera shown in my copending application, led November 2,1933, given Serial No. 696,313. Referring particularly to Fig. 1 myincandescent projecting lamps II, I2, and I3 are employed for projectinglight through frames I 3, I5, and i5 of iilm I1. The projection framesI5, l5 and I5 are spaced apart on iilm I1 so that a projection frameseparates frames Id and I5, and frames i5 and I6. Thus frames I5, I5 andI6 are projected at one time and upon a subsequent movement of the iilmI1 the intermediate frames are projected. The alternate spacing of theframes and the alternate projection of themv diminishes the necessaryrectilinear motion of the lm I1 between successive projections. Thesethree frames just mentioned are projected simultaneously and thrown uponscreen I8 and present superimposed images of the object which wasphotographed from one point of view. Condensing reflectors I9, 2li, andZI are employed for directing the light rays of the projecting lampsthrough condensing lenses 22, 23, and 25 which make the rays parallel.The parallel light rays from the condensing -lenses just mentioned arethence reected at the angle of polarization by' highlypolished,unsilvered reflecting surfaces 25, 25, and 21. The reflecting surfacesjust mentioned polarize the light rays in parallel planes and reect themthrough condensing lenses 28, 23, and 35, from which the light rays passthrough lm frames lll, I5, and I5 respectively.

A framing' plate 3l is preferably employed for framing the light raysfor passage through the various hn frames.

The monochrome images formed by the passage of light rays through thevarious iilni frames are transmitted by'lenses 32, 33, and 35 toprojecting lenses 35, 3G, and. 31 respectively. As before stated theimages are monochrome images of the various colors photographed and inorder to project the images in the original color I preferablylinterpose color lters 38, 39, and l0 between lenses 35, 35, and 31respectively and screen I8 so as to cause the monochrome imagestransmitted by lenses 35, 35, and 31 to be projected in the colors forwhich they are records and superimposed upon screen I 8. My preferredmethod and apparatus for producing color lm are also disclosed in anapplication led by me on September 22, 1933, given Serial No. 690,555,and entitled Method and apparatus for photography and-I projection. Thelight rays of the colored image on screen I8 are then received by myanalyzing means or Nicols elongated rhombohedron prisms l of Icelandspar l I.

Since the light rays reflected by reecting surfaces 25, 25, and 21 arepolarized in the same parallel planes as analyzing means lil lwillpolarize light, the light rays pass to the eyes of the observer and heobserves the photographed image of the object-in color as viewed fromone viewpoint.

'l'oA produce third dimension or stereoscopic aocacec eect it is ofcourse necessary to project an' image of the object photographedsimultaneously from a spaced point of view for observation by the othereye. For this purpose I preferably employ incandescent projecting lamps52, 53, and dll and condense their rays by condensing reflectors 35, Q5,and 51. The light rays pass through condensing lenses d8, 59, and 5i?,respectively and emerge parallel and are reected by plane polarizingmeans 5I, 52, and 53 respectively. The polarizing means just mentionedare similar in all respects to polarizing means 25, 25, and 21.Polarizing means 25, 26, and 2,1 are rotated about the axis of theincident light 90 degrees relative to said last mentioned polarizingmeans. By so arranging polarizing means 5 I, 52, and 53, the light raysfrom the projection lamps are polarized in planes at an angle of '90degrees to the planes of polarized light rays reeeted by polarizingmeans 25, 25, and 21. From polarizing reiiectors 5I, 52,

and 53, the light rays are reflected through conmitted by lenses 6B, 5I,and 32 to projecting lenses 53, 65, and 55. The images transmitted bysaid projecting lenses are in monochrome and in y order to project theimages in original colors, the light rays from said projecting lensesarepassed through color filters 66, 61, and 58 similar. to those used inphotographing records and received on screen It. The plurality of imagesare superimposed onv screen I8 and reproduce an image in original colorsof the object photographed from a point of View. spaced from the pointof view from which the images projected byl projecting lenses 35, 36,and 31 were photographed. The superimposed images on screenv I8 whichare projected for observation by the left eye are received by polarizingmeans or Nicols prism 59 which permits passage of light rays polarizedinY the same planes and thus for the left eye, but the light rays fromthe image for the righteye are not permitted to pass polarizing means 53since said image is polarized in planes at 90 degrees to the planes ofpolarization of polarizing means'63.

As before stated, one of my objects is to increase illumination Which islost with the ordi,- nary projection machine when the various lm framesare advanced and a shutter is employed to conceal such advancement andeliminate blurring. While it is not discernible to the human eye, theshutter of the ordinary projecting machine periodically shuts off thelight from the projecting lamp. I propose to eliminate the shutter andproject one series of frames while another series is being'advanced. Inorder to accomplish this I extinguish the projecting lampsA employed forone series of frames while the of iilms, the exposure of which is setout-in dei' tail in my application entitled Camel-aand method ofphotography, Serial No. 696,313, iiled November 2. 1933. As there stated.I `record a multiplicity of images of'the samesubject desired to bephotographed from one point of view and simultaneously record amultiplicity of images of the subject from a spaced point of view. Eachof the images is amonochrome record of one color of the subject and bysuperimposing the plurality of images in projection I am able toreproduce the desired color eects of the subject. In my apparatus andmethod disclosed in said application I preferably expose one series offrames of one lm during the time another lm having a series of frames isbeing advanced to position for exposure. The apparatus there disclosedemploys a shutter which is adapted to cover each film during its periodof advancement, but in the present projection machine I eliminate anyshutter means by employing the above mentioned commutator means.

In projecting the film described in the paragraph immediately above, itis necessary to employ duplicate projecting means and polarizing meansand consequently I arrange projecting means and polarizing meansimmediately below the projecting means described in Fig. 1 which aresimilar in all respects to the projecting means described in connectionwith Fig, l for projecting another lm while the upper film `is beingshifted and advanced for a subsequent projection of other images of themoving object. Figs. 2 and 5 illustrate in side elevation the relativepositions of the upper'and lower rows of projecting means and polarizingmeans employed for the left and right eyes respectively. For syn'-chronously advancing and projecting said upper and lower films Ipreferably employ the means above mentioned and hereinafter set out in ydetail.

- keyed adjacent its lower end and a bevel gear 82 keyed adjacent itsupper end. A bevel gear 83 is keyed to a horizontal shaft 84 and mesheswith gear 82 vfor the purpose of driving shaft 84. A bevel gear 85 iskeyed to the .opposite end of shaft 84 and meshes with a bevel gear 86which is keyed to a shaft 81 on which sprocket 19 is keyed. Ap-

propriate bearing supports for shafts 80, 84, and

' 81 are anchored to the walls of housing 88. A

similar arrangement of parts is provided for advancing lower lm 89, andspur gear 90 is the gear which is intermittently driven to cause theintermittent actuation of the lower advancing mechanism. A

A'vertical shaft 9| is anchored in appropriate bearings which aresupported by the walls of housing 88 and has keyed thereto a mutilatedgear 92 which has an upper set of teeth 93 and a lower set 94.' As canbe seen particularly the teeth 93 and 94 will drive gears 8| and 90 atstaggered periods of time; A bevel gear 95 is keyed to shaft 9| andadapted to be driven by a drive bevel gear 96 which is keyed to a powershaft 91. A commutator generally indicated at 98 is keyed to shaft 9 Iand adapted to cause the intermittent extinguishment and lighting of theprojection lamps employed with the upper lm I1 and lower film 89.

The electrical circuits and commutator may be more easily understood byreferring to Figs. 4, 5, and 6. `A lighting switch 99 is introducedbetween power supplylines I00-and IOI, and supply lines |02 and |03. Awire |04 is electrically connected with supply wire I 02 and one contactof lower projection lamps. The supply wire |02 is electrically connectedwith one contact of the upper row of projection lamps. Wire |03iselectrically connected with one contact of switch 99 and with terminal|05 of a brush contact member |06. The other contact member |01 of thebrush contact member |06 is electrically connected by wire |08 with theremaining contact members of the lower projection lamps. An upper brush|09 is separated from lower brush I|0 by appropriate insulation materialand when contact band III is moving on the ends of brushes |09 and I I0a circuit is closed to the lower projecting lamps. The contact band I Iis arranged on the periphery of the body of. vrotatable commutator 98and thus causes the lower projection lamps to be lighted duringsubstantially 180 degrecs of the rotation of commutator 98. A wire II2electrically connects wire |03 with contact II3 of brush contact memberI|4 and a contact 20 member |I5 is connected electrically by wire ||6with the remaining contact of upper projection lamps. Brushes II1 andII8 of brush contact member I|4 are separated by appropriate insulationmaterial and close avcircuit to the upper 25 projection lamps whencontact band II9 bridges the gap between brushes II1 and I|8 duringrotation of commutator 98. 'Ihe contact band I9 is arranged on theperiphery of the commutator and extends through substantially 180degrees of 30 the periphery of the commutator; the contact bands I IIand IIS are placed opposite each other on commutator 98 and are arrangedin separated vertical planes. It can thus be seen that when band I II isclosing a circuit to the lower projection lamps the circuit to the upperprojection lamps is broken because the band ||9 is not in contact withbrushes H1 and H8. Likewise, when band M9 is closing a circuit to theupper projection lamps the lower lamps are extinguished because the bandIII is not in contact with brushes |09 and IIO. The brush contactmembers |06 and I I4 are supported by an appropriatebracket I 20 whichis anchored to the wall of housing 88 and said brush contact members arearranged for sliding movement toward commutator 98 and are urged towardsaid commutator by appropriate coil springs which bear against collarsanchored on the slidable shafts I2| and I 22 which support brush contactmembers II4 and |06, respectively.

Referring again to Fig. 8, it can .be seen that the various frames ofupper film I1 are being projected because contact band II9 is closing acir- -cuit between brushes II1 and I|8 to the upper the teeth 94 are inmesh with and driving spur' The lower projection lamps are not gear 90.lighted because contact band III is not closing a circuit betweenbrushes |09 and ||0 to the lower projection lamps. However, as shaft 9|continues to rotate, the contact band I I9 will leave brushes I I1 andIIB and open the circuit to the upper projection lamps. -At virtuallythe same moment that the upper projection lamps areextinguished thelower projection lamps will be lighted by contact band III. closing thecircuit between the brushes of brush contact member |06 to the lowerprojection lamps. When the upper projection lamps are extinguished theupper film will be advanced as soon as teeth 93 mesh with spur gear bandH9 leaves brushes lll and H3.) vancement of. the lower nlm will havebeen completed at substantially the same moment that contact band lilreaches brushes l@ and il@ in r its rotation.

As stated beforethe film best adapted. for use in this stereoscopicprojecting apparatus is made by exposure in my stereoscopic cameradescribed in application filed November 2, 1933, and given Serial No.696,313. As there stated, each of the lms is advanced a total of sixframes at one time and remains stationary during the advancement oftheother iilm through a period of six frames. Since it is not necessarywith this proy jection apparatus to employ a shutter the promore time isgiven for projection. Thisresults'.

in particular to the advantage of my stereoscopic projection machinessince the amount of illuminatiqn is increased by the increasedprojection period and also added illumination dueto superimposedprojection by multiple light sources.

My apparatus illustrated has the projecting and polarizing means for onelm arranged above the like means -for the other lm, but the projectingand polarizing means for one lm may. be 'easily arranged laterally ofthe like means for the other lm so that both lms may travel verticallyinstead o! horizontally.

I have explained my invention in connection "with the use of nlm whichhas been exposed m adsense bi. (This will be at the moment that contactThe admy apparatus described in my application for patent entitled,"Camera and method of phov tography, Serial No, 696,313, led November 2,1933. However, even though I preferably employ a multiplicity of lms asthey are described, any

arrangement of frames on any number of lms might be employed with adegree of success in order to obtain stereoscopiceiect withthe use ofpolarized light.

While I have shown and described my prenot wish to be limited to thedetails of method or apparatus herein shown, but wish to avail myself ofall variations of apparatus and method coming within the scope of theappended claim. I

Having thus described my invention Awhat I claim as new and desire tosecure by Letters Patent is: f

The method of projecting stereoscopic pictures in color, comprisingprojecting aseries of lm frames carrying images of a photographicsubject protographed from one point of view and simultaneouslyprojecting from the same lm another series of lm frames carrying, imagesof said subject photographed from a spaced point of view, each of saidseries having each of its ferred method and form of construction I doframes spaced away one frame from theclosest frame in its respectiveseries, ltering the light rays of said projected images withvcolor ltermeans, advancing said lm a number of frames projected during oneprojection; subsequently projecting the unprojected spacing frames, andsimultaneously projecting a series of spaced frames on another filmduring the said last mention'ed step of advancing said rst mentioned'.ALLENILBARNES.

